Reaction Mechanisms in Shocked, Intercalated Graphite and Boron Nitride

Abstract

The traditional ways of developing increasingly energetic materials usually lead to an increase in shock and impact sensitivities. It is, therefore, of practical and theoretical importance to design model, highly-energetic polycrystalline systems which will clearly indicate, at the molecular level, the interplay between the shock-induced reaction mechanisms and the associated excited lattice states. Theoretical and experimental studies indicate that such systems may possibly be constructed from special materials such as high-quality pyrolytic, layered graphite and hexagonal boron nitride (BN) crystals. Although each layer of graphite and BN is one of the most stable structures in nature, intercalation of the crystals with various oxidizing agents can yield energetic systems with the desired properties. As an example, intercalation with HNO3 gives crystals of density 2.20 g/cc. The optimal positioning of the HNO3 molecules between the BN layers allows the rapid formation of B2O3 in a single step with a large release of energy. A possible triggering mechanism is the shock-induced, partial sp3 hybridization of the layers as a result of kink band formation.